Computers consume electrical energy to operate. They consume electrical energy even when they are apparently idle. An idle computer may consume up to 60% of its fully active power consumption. That is wasteful. Large server farms having hundreds or even thousands of servers consume very large amount of power. The power consumed by a computer is released as heat and server rooms thus require air conditioning equipment which in turn also consume power.
In large server farms, it is likely that some or even many servers are idle for at least part of the time and some may even be idle most to the time. Idle servers waste power and take up space which may be better utilised. Thus it is desirable to monitor the performance of servers and computers in general so as to, for example, identify computers which are not performing a useful purpose.
Servers may be virtualised. Whilst power consumption is not attributable to a virtual server in the same way as to a “real” server, a virtual server requires computing resources which are wasted if the virtual server serves no useful purpose. As with real servers, virtual servers may be idle for part of even most of the time and it is thus desirable to monitor the performance of virtual servers or virtual computers in general so as to, for example, identify virtual computers which are not performing a useful purpose.